Conventionally, a communication device for use in a vehicle transmits an emergency signal to an emergency service center through a radio communication unit, and receives an incoming call from the service center in waiting state. At the same time, the communication device receives a reset signal from an external device for resetting and restarting. Therefore, the reset signal received from the external device interrupts the waiting state of the communication device.
For example, an input such as an emergency button signal from an emergency button, an airbag deployment signal from an airbag ECU arranges the communication device in waiting state of an emergency operation for reception of the incoming call from the service center after transmission of the emergency signal to the service center. At approximately the same time, the same communication device receives the reset signal for synchronous startup operation of the communication device with a navigation system that is connected thereto through a USB interface. In this case, the communication device in waiting for the incoming call after the transmission of the emergency signal to the service center is put into reset operation before receiving the incoming call. As a result, the emergency operation of the communication device is interrupted and aborted.
The communication device disclosed in Japanese patent document JP-2005-58950 uses a non-volatile memory for storing an operation status of the communication device. That is, the emergency operation of the communication device is stored in the memory once the communication device has started the emergency operation. In this manner, the communication device refers to the non-volatile memory and resumes the emergency operation after resetting the communication device in a case where the emergency operation is interrupted by the reset signal received from the external device.
However, the communication device disclosed in the above document cannot answer the incoming call from the service center until it finishes the reset operation once the device is put into a process of the reset operation upon receiving the reset signal from the external device.